Note that by default wxSingleInstanceChecker::CreateDefault() is used to create the checker meaning that it will be initialized differently for different users and thus will allow different users to run the application concurrently which is usually the required behaviour. However if only a single instance of a program should be running system-wide, you need to call Create() with a custom name which does not include wxGetUserId().

This class is implemented for Win32 and Unix platforms (supporting fcntl() system call, but almost all of modern Unix systems do) only.

Member Function Documentation

Initialize the object if it had been created using the default constructor.

Note that you can't call Create() more than once, so calling it if the non default ctor had been used is an error.

Parameters

name

Must be given and be as unique as possible. It is used as the mutex name under Win32 and the lock file name under Unix. wxApp::GetAppName() and wxGetUserId() are commonly used to construct this parameter.

path

The path is optional and is ignored under Win32 and used as the directory to create the lock file in under Unix (default is wxGetHomeDir()).

Returns

Returns false if initialization failed, it doesn't mean that another instance is running – use IsAnotherRunning() to check for it.

Note

One of possible reasons while Create() may fail on Unix is that the lock file used for checking already exists but was not created by the user. Therefore applications shouldn't treat failure of this function as fatal condition, because doing so would open them to the possibility of a Denial of Service attack. Instead, they should alert the user about the problem and offer to continue execution without checking if another instance is running.